While popularly known for his role as
one of the United States founding fathers, Benjamin Franklin was also a
renowned scientist who made a number of substantial contributions in the
field of Earth science. Affectionately known as Dr. Franklin (even
though he never received his Ph.D.), he published numerous scientific
papersmostly on electricity. Franklin became a scientist because he
was insatiably curious about the world around him. He wanted to know how
things worked and figure out ways to make them better.

In 1743, Franklin compared weather observations in letters he received
from friends in other colonies. He was one of the first to observe that
North American storms tend to move from west to east, and predicted that
a storm's course could be plotted. He even made some of the
first-recorded weather forecasts in his Poor Richards Almanac, a
25-year publication that Franklin first published in 1732 under the
pseudonym of Richard Saunders.

In 1752, Franklin, along with his son William, performed his famous
kite-flying experiment which proved that lightning is a
naturally-occurring electrical phenomenon. The kite was constructed with
a sharp metallic wire situated on top and at the end of the kite string,
and a key tied to the end of the string with a silk ribbon. When
Franklin saw loose threads on the kite string stand up, he grounded the
makeshift insulated conductor by touching his knuckle to the metal key
on the string. Consequently, he observed a passing spark between his
knuckle and the key, which presented the final proof of lightning's
electrical nature. Miraculously, the charge was not strong enough to be
fatal to Franklin or his son. (Under normal circumstances, a lightning
strike can instantly kill any individuals bold enough to fly a kite
during a thunderstorm.)

Bottom: Franklin and his son, William, performing their legendary experiment in the midst of a thunderstorm. Courtesy Library of Congress

In 1763, Franklin took part in discussions with colonial scholars about
the effects of deforestation on local climate. As forests were cleared
for farming in the early American colonies, Franklin agreed with the
other colonials that "cleared land absorbs more heat and melts snow
quicker." However, he thought that many years of observations were
necessary before any conclusive evidence could be gathered on the
effects of deforestation on the local climate.

In addition to his meteorological prowess, Franklin also published the
first scientific chart of the North Atlantics Gulf Stream. He
hypothesized that the trade winds cause the Gulf Stream by driving warm
waters into the Gulf of Mexico, from where they exit by way of the
Florida Strait and proceed to form the Gulf Stream. In 1775, on his way
to England, Franklin lowered a thermometer into the Atlantic and found
the Gulf Stream to be 6° F warmer than the surrounding sea and,
subsequently, produced the first chart of the current.

In the last years of his life, Franklin conducted studies on the effects
that volcanic eruptions might have on weather patterns, cloud formation,
and cloud electrification. He hypothesized that the severe Northern
Hemisphere winter of 178384 was linked to the volcanic eruption
occurring in Iceland in the summer of 1783. Franklin suggested that
there was a reduction in the amount of solar energy received at the
Earth's surface after the volcanic eruption due to the ash and other
particles inserted into the atmosphere.

ImageA sea surface temperature map of the Gulf Stream. The warm waters of the
Gulf Stream (orange and red) emerge from the Gulf of Mexico, flow up the U.S.
Atlantic coast, and eventually turn east towards Europe while they slowly cool.
The surrounding ocean is as much as 6 degrees Fahrenheit cooler (blue and green)
Image courtesy NASA SeaWiFS project, based on NOAA data.

Internet ReferencesBenjamin Franklin: A Documented History
J.A. Leo Lemay
University of Delaware
Department of English